Please help me it would be very much appreciated!

Answer:
28
Step-by-step explanation:
So in this question, we know that n is now 21. So if we substitute n with 21, we get
[tex]-2 +\frac{3}{2}(21 -1)[/tex]
[tex]= -2 + \frac{3}{2}(20)[/tex]
[tex]=-2+\frac{60}{2}[/tex]
[tex]=-2 + 30[/tex]
[tex]= 28[/tex]
Which is our answer.